code: def postag_tree(tree):
      # Part-of-speech tagging.
      words = tree.leaves()
      tag_iter = (pos for (word, pos) in pos_tag(words))
      newtree = Tree("S", [])
      for child in tree:
          if isinstance(child, Tree):
              newtree.append(Tree(child.label(), []))
              for subchild in child:
                  newtree[-1].append((subchild, next(tag_iter)))
          else:
              newtree.append((child, next(tag_iter)))
      return newtree
  
imports: import os
  import pickle
  import re
  from xml.etree import ElementTree
  from nltk.tag import ClassifierBasedTagger, pos_tag
  from nltk.chunk.api import ChunkParserI
  from nltk.chunk.util import ChunkScore
  from nltk.data import find
  from nltk.tokenize import word_tokenize
  from nltk.tree import Tree
label_desc: Use image node_id 3 for calling a global function with example usage: postag_tree(tree) and returns: newtree